Android开发使用Dom从网络端解析xml文件

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本程序实现了从网络端解析xml文件，展示在列表，并实现点击进入相关页面。

首先我们创建一个类，用来实现http请求和xml文件节点的获取

public class XMLParser {

    // constructor
    public XMLParser() {

    }

    /**
     * Getting XML from URL making HTTP request
     * @param url string
     * */
    public String getXmlFromUrl(String url) {
        String xml = null;
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            xml = EntityUtils.toString(httpEntity,"utf-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // return XML
        return xml;
    }
    
    /**
     * Getting XML DOM element
     * @param XML string
     * */
    public Document getDomElement(String xml){
        Document doc = null;
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        try {

            DocumentBuilder db = dbf.newDocumentBuilder();

            InputSource is = new InputSource();
                is.setCharacterStream(new StringReader(xml));
                doc = db.parse(is); 

            } catch (ParserConfigurationException e) {
                Log.e("Error: ", e.getMessage());
                return null;
            } catch (SAXException e) {
                Log.e("Error: ", e.getMessage());
                return null;
            } catch (IOException e) {
                Log.e("Error: ", e.getMessage());
                return null;
            }

            return doc;
    }
    
    /** Getting node value
      * @param elem element
      */
     public final String getElementValue( Node elem ) {
         Node child;
         if( elem != null){
             if (elem.hasChildNodes()){
                 for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
                     if( child.getNodeType() == Node.TEXT_NODE  ){
                         return child.getNodeValue();
                     }
                 }
             }
         }
         return "";
     }
     /**
      * Getting node value
      * @param Element node
      * @param key string
      * */
     public String getValue(Element item, String str) {        
            NodeList n = item.getElementsByTagName(str);        
            return this.getElementValue(n.item(0));
        }
}

然后我们创建一个Activity继承与ListActivity，在这个Activity中定义一些节点。

public class AndroidXMLParsingActivity extends ListActivity {

    // All static variables
    static final String URL = "http://10.0.2.2/biyeshejidata/menu.xml";
    // XML node keys
    static final String KEY_ITEM = "item"; // parent node
    static final String KEY_ID = "id";
    static final String KEY_NAME = "name";
    static final String KEY_COST = "cost";
    static final String KEY_DESC = "description";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        ArrayList<HashMap> menuItems = new ArrayList<HashMap>();

        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(URL); // getting XML
        Document doc = parser.getDomElement(xml); // getting DOM element

        NodeList nl = doc.getElementsByTagName(KEY_ITEM);
        // looping through all item nodes 
        for (int i = 0; i < nl.getLength(); i++) {
            // creating new HashMap
            HashMap map = new HashMap();
            Element e = (Element) nl.item(i);
            // adding each child node to HashMap key => value
            map.put(KEY_ID, parser.getValue(e, KEY_ID));
            map.put(KEY_NAME, parser.getValue(e, KEY_NAME));
            map.put(KEY_COST, "Rs." + parser.getValue(e, KEY_COST));
            map.put(KEY_DESC, parser.getValue(e, KEY_DESC));

            // adding HashList to ArrayList
            menuItems.add(map);
        }

        // Adding menuItems to ListView
        ListAdapter adapter = new SimpleAdapter(this, menuItems,
                R.layout.list_item,
                new String[] { KEY_NAME, KEY_DESC, KEY_COST }, new int[] {
                        R.id.name, R.id.desciption, R.id.cost });

        setListAdapter(adapter);

        // selecting single ListView item
        ListView lv = getListView();

        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // getting values from selected ListItem
                String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
                String cost = ((TextView) view.findViewById(R.id.cost)).getText().toString();
                String description = ((TextView) view.findViewById(R.id.desciption)).getText().toString();
                
                // Starting new intent
                Intent in = new Intent(getApplicationContext(), SingleMenuItemActivity.class);
                in.putExtra(KEY_NAME, name);
                in.putExtra(KEY_COST, cost);
                in.putExtra(KEY_DESC, description);
                startActivity(in);

            }
        });
    }
}

最后实现点击进入一个新的页面的Activity。

public class SingleMenuItemActivity  extends Activity {
    
    // XML node keys
    static final String KEY_NAME = "name";
    static final String KEY_COST = "cost";
    static final String KEY_DESC = "description";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.single_list_item);
        
        // getting intent data
        Intent in = getIntent();
        
        // Get XML values from previous intent
        String name = in.getStringExtra(KEY_NAME);
        String cost = in.getStringExtra(KEY_COST);
        String description = in.getStringExtra(KEY_DESC);
        
        // Displaying all values on the screen
        TextView lblName = (TextView) findViewById(R.id.name_label);
        TextView lblCost = (TextView) findViewById(R.id.cost_label);
        TextView lblDesc = (TextView) findViewById(R.id.description_label);
        
        lblName.setText(name);
        lblCost.setText(cost);
        lblDesc.setText(description);
    }
}